[for-4.13,v2] xen/arm: domain_build: Don't expose IOMMU specific properties to hwdom
diff mbox series

Message ID 1570548304-12020-1-git-send-email-olekstysh@gmail.com
State Superseded
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Series
  • [for-4.13,v2] xen/arm: domain_build: Don't expose IOMMU specific properties to hwdom
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Commit Message

Oleksandr Oct. 8, 2019, 3:25 p.m. UTC
From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>

We don't passthrough IOMMU device to hwdom even if it is not used by Xen.
Therefore exposing the properties that describe relationship between
master devices and IOMMUs does not make any sense.

According to the:
1. Documentation/devicetree/bindings/iommu/iommu.txt
2. Documentation/devicetree/bindings/pci/pci-iommu.txt

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>

---
Changes V1 [1] -> V2:
   - Only skip IOMMU specific properties of the master device if we
     skip the corresponding IOMMU device
   - Use "hwdom" over "Dom0"

[1] https://lists.xenproject.org/archives/html/xen-devel/2019-10/msg00104.html
---
 xen/arch/arm/domain_build.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

Comments

Julien Grall Oct. 10, 2019, 3:18 p.m. UTC | #1
Hi,

On 10/8/19 4:25 PM, Oleksandr Tyshchenko wrote:
> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
> 
> We don't passthrough IOMMU device to hwdom even if it is not used by Xen.
> Therefore exposing the properties that describe relationship between
> master devices and IOMMUs does not make any sense.
> 
> According to the:
> 1. Documentation/devicetree/bindings/iommu/iommu.txt
> 2. Documentation/devicetree/bindings/pci/pci-iommu.txt

It is not entirely clear that documentation is from Linux.

> 
> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
> 
> ---
> Changes V1 [1] -> V2:
>     - Only skip IOMMU specific properties of the master device if we
>       skip the corresponding IOMMU device
>     - Use "hwdom" over "Dom0"
> 
> [1] https://lists.xenproject.org/archives/html/xen-devel/2019-10/msg00104.html
> ---
>   xen/arch/arm/domain_build.c | 29 +++++++++++++++++++++++++++++
>   1 file changed, 29 insertions(+)
> 
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index 6d6dd52..a7321b8 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -480,10 +480,26 @@ static int __init write_properties(struct domain *d, struct kernel_info *kinfo,
>       const struct dt_property *prop, *status = NULL;
>       int res = 0;
>       int had_dom0_bootargs = 0;
> +    struct dt_device_node *iommu_node;
>   
>       if ( kinfo->cmdline && kinfo->cmdline[0] )
>           bootargs = &kinfo->cmdline[0];
>   
> +    /*
> +     * If we skip the IOMMU device when creating DT for hwdom (even if
> +     * the IOMMU device is not used by Xen), we should also skip the IOMMU
> +     * specific properties of the master device behind it in order to avoid
> +     * exposing an half complete IOMMU bindings to hwdom.
> +     * Use "iommu_node" as an indicator of the master device which properties
> +     * should be skipped.
> +     */
> +    iommu_node = dt_parse_phandle(node, "iommus", 0);

The code is slightly confusing to read. I don't think we should care of 
invalid DT here, so let's only consider valid one.

For valid DT, any non-NULL return should point to an IOMMU. The comment 
above suggests that all IOMMU will be skipped. However, the check below 
(device_get_class(iommu_node)) will not return DEVICE_IOMMU when there 
are not have a driver for the IOMMU.

So this needs to be clarified in the commit message.

> +    if ( iommu_node )
> +    {
> +        if ( device_get_class(iommu_node) != DEVICE_IOMMU )
> +            iommu_node = NULL;
> +    }

Could we gather the two conditions in one if?

> +
>       dt_for_each_property_node (node, prop)
>       {
>           const void *prop_data = prop->value;
> @@ -540,6 +556,19 @@ static int __init write_properties(struct domain *d, struct kernel_info *kinfo,
>               continue;
>           }
>   
> +        if ( iommu_node )
> +        {
> +            /* Don't expose IOMMU specific properties to hwdom */
> +            if ( dt_property_name_is_equal(prop, "iommus") )
> +                continue;
> +
> +            if ( dt_property_name_is_equal(prop, "iommu-map") )
> +                continue;
> +
> +            if ( dt_property_name_is_equal(prop, "iommu-map-mask") )
> +                continue;
> +        }
> +
>           res = fdt_property(kinfo->fdt, prop->name, prop_data, prop_len);
>   
>           if ( res )
> 

Cheers,
Oleksandr Oct. 10, 2019, 3:27 p.m. UTC | #2
On 10.10.19 18:18, Julien Grall wrote:
> Hi,

Hi Julien


>
> On 10/8/19 4:25 PM, Oleksandr Tyshchenko wrote:
>> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
>>
>> We don't passthrough IOMMU device to hwdom even if it is not used by 
>> Xen.
>> Therefore exposing the properties that describe relationship between
>> master devices and IOMMUs does not make any sense.
>>
>> According to the:
>> 1. Documentation/devicetree/bindings/iommu/iommu.txt
>> 2. Documentation/devicetree/bindings/pci/pci-iommu.txt
>
> It is not entirely clear that documentation is from Linux.

Will clarify.


>
>>
>> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
>>
>> ---
>> Changes V1 [1] -> V2:
>>     - Only skip IOMMU specific properties of the master device if we
>>       skip the corresponding IOMMU device
>>     - Use "hwdom" over "Dom0"
>>
>> [1] 
>> https://lists.xenproject.org/archives/html/xen-devel/2019-10/msg00104.html
>> ---
>>   xen/arch/arm/domain_build.c | 29 +++++++++++++++++++++++++++++
>>   1 file changed, 29 insertions(+)
>>
>> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
>> index 6d6dd52..a7321b8 100644
>> --- a/xen/arch/arm/domain_build.c
>> +++ b/xen/arch/arm/domain_build.c
>> @@ -480,10 +480,26 @@ static int __init write_properties(struct 
>> domain *d, struct kernel_info *kinfo,
>>       const struct dt_property *prop, *status = NULL;
>>       int res = 0;
>>       int had_dom0_bootargs = 0;
>> +    struct dt_device_node *iommu_node;
>>         if ( kinfo->cmdline && kinfo->cmdline[0] )
>>           bootargs = &kinfo->cmdline[0];
>>   +    /*
>> +     * If we skip the IOMMU device when creating DT for hwdom (even if
>> +     * the IOMMU device is not used by Xen), we should also skip the 
>> IOMMU
>> +     * specific properties of the master device behind it in order 
>> to avoid
>> +     * exposing an half complete IOMMU bindings to hwdom.
>> +     * Use "iommu_node" as an indicator of the master device which 
>> properties
>> +     * should be skipped.
>> +     */
>> +    iommu_node = dt_parse_phandle(node, "iommus", 0);
>
> The code is slightly confusing to read. I don't think we should care 
> of invalid DT here, so let's only consider valid one.

Do you mean "the comment" is confusing to read?


>
> For valid DT, any non-NULL return should point to an IOMMU. The 
> comment above suggests that all IOMMU will be skipped. However, the 
> check below (device_get_class(iommu_node)) will not return 
> DEVICE_IOMMU when there are not have a driver for the IOMMU.
>
> So this needs to be clarified in the commit message.

Will do.


>
>> +    if ( iommu_node )
>> +    {
>> +        if ( device_get_class(iommu_node) != DEVICE_IOMMU )
>> +            iommu_node = NULL;
>> +    }
>
> Could we gather the two conditions in one if?

Yes.
Julien Grall Oct. 10, 2019, 3:32 p.m. UTC | #3
Hi,

On 10/10/19 4:27 PM, Oleksandr wrote:
> 
> On 10.10.19 18:18, Julien Grall wrote:
>> Hi,
> 
> Hi Julien
> 
> 
>>
>> On 10/8/19 4:25 PM, Oleksandr Tyshchenko wrote:
>>> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
>>>
>>> We don't passthrough IOMMU device to hwdom even if it is not used by 
>>> Xen.
>>> Therefore exposing the properties that describe relationship between
>>> master devices and IOMMUs does not make any sense.
>>>
>>> According to the:
>>> 1. Documentation/devicetree/bindings/iommu/iommu.txt
>>> 2. Documentation/devicetree/bindings/pci/pci-iommu.txt
>>
>> It is not entirely clear that documentation is from Linux.
> 
> Will clarify.
> 
> 
>>
>>>
>>> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
>>>
>>> ---
>>> Changes V1 [1] -> V2:
>>>     - Only skip IOMMU specific properties of the master device if we
>>>       skip the corresponding IOMMU device
>>>     - Use "hwdom" over "Dom0"
>>>
>>> [1] 
>>> https://lists.xenproject.org/archives/html/xen-devel/2019-10/msg00104.html 
>>>
>>> ---
>>>   xen/arch/arm/domain_build.c | 29 +++++++++++++++++++++++++++++
>>>   1 file changed, 29 insertions(+)
>>>
>>> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
>>> index 6d6dd52..a7321b8 100644
>>> --- a/xen/arch/arm/domain_build.c
>>> +++ b/xen/arch/arm/domain_build.c
>>> @@ -480,10 +480,26 @@ static int __init write_properties(struct 
>>> domain *d, struct kernel_info *kinfo,
>>>       const struct dt_property *prop, *status = NULL;
>>>       int res = 0;
>>>       int had_dom0_bootargs = 0;
>>> +    struct dt_device_node *iommu_node;
>>>         if ( kinfo->cmdline && kinfo->cmdline[0] )
>>>           bootargs = &kinfo->cmdline[0];
>>>   +    /*
>>> +     * If we skip the IOMMU device when creating DT for hwdom (even if
>>> +     * the IOMMU device is not used by Xen), we should also skip the 
>>> IOMMU
>>> +     * specific properties of the master device behind it in order 
>>> to avoid
>>> +     * exposing an half complete IOMMU bindings to hwdom.
>>> +     * Use "iommu_node" as an indicator of the master device which 
>>> properties
>>> +     * should be skipped.
>>> +     */
>>> +    iommu_node = dt_parse_phandle(node, "iommus", 0);
>>
>> The code is slightly confusing to read. I don't think we should care 
>> of invalid DT here, so let's only consider valid one.
> 
> Do you mean "the comment" is confusing to read?

The code is confusing because "iommus" should always point to a IOMMU 
node, but then you check whether this is an IOMMU. So it is not clear if 
this is done for sanity check (or for a different reason).

Cheers,
Oleksandr Oct. 10, 2019, 3:42 p.m. UTC | #4
On 10.10.19 18:32, Julien Grall wrote:
> Hi,

Hi


>
>>>> [1] 
>>>> https://lists.xenproject.org/archives/html/xen-devel/2019-10/msg00104.html 
>>>>
>>>> ---
>>>>   xen/arch/arm/domain_build.c | 29 +++++++++++++++++++++++++++++
>>>>   1 file changed, 29 insertions(+)
>>>>
>>>> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
>>>> index 6d6dd52..a7321b8 100644
>>>> --- a/xen/arch/arm/domain_build.c
>>>> +++ b/xen/arch/arm/domain_build.c
>>>> @@ -480,10 +480,26 @@ static int __init write_properties(struct 
>>>> domain *d, struct kernel_info *kinfo,
>>>>       const struct dt_property *prop, *status = NULL;
>>>>       int res = 0;
>>>>       int had_dom0_bootargs = 0;
>>>> +    struct dt_device_node *iommu_node;
>>>>         if ( kinfo->cmdline && kinfo->cmdline[0] )
>>>>           bootargs = &kinfo->cmdline[0];
>>>>   +    /*
>>>> +     * If we skip the IOMMU device when creating DT for hwdom 
>>>> (even if
>>>> +     * the IOMMU device is not used by Xen), we should also skip 
>>>> the IOMMU
>>>> +     * specific properties of the master device behind it in order 
>>>> to avoid
>>>> +     * exposing an half complete IOMMU bindings to hwdom.
>>>> +     * Use "iommu_node" as an indicator of the master device which 
>>>> properties
>>>> +     * should be skipped.
>>>> +     */
>>>> +    iommu_node = dt_parse_phandle(node, "iommus", 0);
>>>
>>> The code is slightly confusing to read. I don't think we should care 
>>> of invalid DT here, so let's only consider valid one.
>>
>> Do you mean "the comment" is confusing to read?
>
> The code is confusing because "iommus" should always point to a IOMMU 
> node, but then you check whether this is an IOMMU. So it is not clear 
> if this is done for sanity check (or for a different reason).

Got it. Will clarify a reason.

Patch
diff mbox series

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 6d6dd52..a7321b8 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -480,10 +480,26 @@  static int __init write_properties(struct domain *d, struct kernel_info *kinfo,
     const struct dt_property *prop, *status = NULL;
     int res = 0;
     int had_dom0_bootargs = 0;
+    struct dt_device_node *iommu_node;
 
     if ( kinfo->cmdline && kinfo->cmdline[0] )
         bootargs = &kinfo->cmdline[0];
 
+    /*
+     * If we skip the IOMMU device when creating DT for hwdom (even if
+     * the IOMMU device is not used by Xen), we should also skip the IOMMU
+     * specific properties of the master device behind it in order to avoid
+     * exposing an half complete IOMMU bindings to hwdom.
+     * Use "iommu_node" as an indicator of the master device which properties
+     * should be skipped.
+     */
+    iommu_node = dt_parse_phandle(node, "iommus", 0);
+    if ( iommu_node )
+    {
+        if ( device_get_class(iommu_node) != DEVICE_IOMMU )
+            iommu_node = NULL;
+    }
+
     dt_for_each_property_node (node, prop)
     {
         const void *prop_data = prop->value;
@@ -540,6 +556,19 @@  static int __init write_properties(struct domain *d, struct kernel_info *kinfo,
             continue;
         }
 
+        if ( iommu_node )
+        {
+            /* Don't expose IOMMU specific properties to hwdom */
+            if ( dt_property_name_is_equal(prop, "iommus") )
+                continue;
+
+            if ( dt_property_name_is_equal(prop, "iommu-map") )
+                continue;
+
+            if ( dt_property_name_is_equal(prop, "iommu-map-mask") )
+                continue;
+        }
+
         res = fdt_property(kinfo->fdt, prop->name, prop_data, prop_len);
 
         if ( res )